In Japanese Unexamined Patent Application Publication No. 9-251723, a method for recording the MSB-end 16 bits and the remaining LSB-end bits of a sample separately from each other is disclosed as a method for recording audio data on DVDs. FIG. 1 is a diagram showing the structure of audio data according to this method. For audio data 43 of data 11 recorded on a DVD, compressed audio data is recorded in some cases and uncompressed audio data is recorded in other cases. As the uncompressed audio data, the audio data 43 encoded by a method called a linear PCM (Pulse Code Modulation) method is recorded. The audio data 43 based on the linear PCM method includes a sample quantized into 24 bits.
In recording the audio data 43 by the linear PCM method onto a DVD, one item of the audio data 43 (audio pack) includes a start code indicating the start of the audio pack and a pack header 64 at the beginning; a packet header 65 including identification information indicating that data included in the relevant audio pack is the audio data 43; additional information AD which is information regarding the audio data 43 included in the relevant audio pack; and a plurality of audio frames AF which are units of a constant playback time for the audio data 43 included in the relevant audio pack AP.
As the additional information AD, information regarding the number of sample bits (24 bits) for sampling the audio data 43 by the linear PCM method, the sampling frequency at that time, and the number of channels included in the relevant audio data 43, etc. is described.
In the audio data 43 for each channel which has been sampled with a number of sample bits of 24, one sample block SPB includes one high-order data block UB including two items of high-order bit data 66 each defining high-order (MSB-end) 16 bits and one low-order data block DB including two items of low-order bit data 67 each defining low-order (LSB-end) 8 bits. One audio frame AF is defined by linking as many relevant sample blocks SPB as corresponding to the above-described constant playback time.
Furthermore, two items of the high-order bit data 66 included in the high-order data block UB include high-order bit data 66A (indicated by “S2n” in the figure) of high-order 16 bits which has been sampled with the timing of even-number-th sampling in relation to the timing of sampling for linear PCM and high-order bit data 66B (indicated by “S2n+1” in the figure) of high-order 16 bits which has been sampled with the timing of odd-number-th sampling in relation to the timing of sampling for linear PCM.
In addition, two items of the low-order bit data 67 included in the low-order data block DB include low-order bit data 67A (indicated by “e2n” in the figure) of low-order 8 bits corresponding to the high-order bit data 66A in relation to the timing of sampling for linear PCM and low-order bit data 67B (indicated by “e2n+1” in the figure) of low-order 8 bits corresponding to the high-order bit data 66B in relation to the timing of sampling for linear PCM. Numbers in parentheses in the high-order bit data 66 and the low-order bit data 67 indicate the number of bits for the respective item of data.
The high-order bit data 66A and the low-order bit data 67A define 24-bit audio data 43 which has been sampled with the timing of even-number-th sampling, and furthermore, the high-order bit data 66B and the low-order bit data 67B define 24-bit audio data 43 which has been sampled with the timing of odd-number-th sampling. Thus, when data is to be played back, the high-order bit data 66A and the low-order bit data 67A are combined for playback, and similarly, the high-order bit data 66B and the low-order bit data 67B are combined for playback.
Furthermore, if four channels “A” to “D” are included, the high-order bit data 66 and low-order bit data 67 includes channel high-order bit data 68 and channel low-order bit data 69 for each channel. In the known art, however, the MSB-end bit data and the LSB-end bit data are recorded separately from each other, and therefore when data is to be played back, the MSB-end bit data and the LSB-end bit data need to be combined. This introduces a problem in that processing by a recording and playback apparatus becomes complicated.